Date: 06/06/11 [[BR]]
Location: Tri Valley[[BR]]
Aircraft: Thor[[BR]]
Pilot: Arion Mangio & James Rosenthal[[BR]]
Flights: 5 Thor[[BR]]
**Weather**[[BR]]
Very hot; sunny, light westerly winds winds, temps around 95F. [[BR]]
METAR KLVN 062053Z AUTO 24004KT 10SM CLR 34/17 A2974 RMK AO2=
[source:/trunk/FlightData Link to Flight Data]
We took Thor to Tri Valley to fly additional anti-windup experiments and some open loop doublets.
No onboard video this trip. The grass has grown significantly, but we were able to find a small space (about 30m x 10m) with short stubble and a few weeds. However, this greatly complicates takeoff and landings and adds significant risk; we either need to fly elsewhere (eg ACRC) or get the grass mowed.
We completed 5 flights with data. GPS performance was still poor (Ticket #22). The flight computer crashed twice; once on the first flight and then once on the ground at the beginning of the day. No indication as to the cause; performed normally the rest of the day.
Controllers were engaged five times on each flight.
For the 4 flights for Jorge Sofrony, the controller used was a modified version of the baseline PI controller, with the following gains:
double pitch_gain[3] = { -0.35, -0.05, 0.10 };[[BR]]
double roll_gain[3] = { -0.30*1.6, -0.05*1.4, 0.05 };
Software used was /branches/thor_flightcode/ rev 422.
Thor Flight 14: (Jorge Sofrony) Nominal controller; anti-windup protection OFF and rate limiting OFF. 5 roll doublet pulses per run.
Thor Flight 15: (Jorge Sofrony) Low order anti-wind up scheme; anti-windup protection ON and rate limiting ON. 5 roll doublet pulses per run.
Thor Flight 16: (Jorge Sofrony) Nominal controller; anti-windup protection OFF and rate limiting ON. 5 roll doublet pulses per run. Large, divergent roll oscillations, reaching close to 90 degrees.
Thor Flight 17: (Jorge Sofrony) Full order anti-wind up scheme; anti-windup protection ON and rate limiting ON. 5 roll doublet pulses per run.
Thor Flight 18: Open loop pitch-yaw-roll doublets to check out alpha-beta probe performance. Doublet periods were too long in pitch, ok for yaw. On the landing approach for this flight, the landing gear caught the tall grass at the edge of the clearing, causing the aircraft to cartwheel. The only damage was the 5-hole probe detached from its mount.
Issues:
1. Observed significant GPS checksum errors. Ticket #22 must be closed out.
2. Either we need to fly elsewhere (eg ACRC) or get the grass at TriValley mowed.
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